Spring is the time to plan your fly strike prevention strategy. It may still be cool in Crookwell and other parts of the Southern Tablelands, but being prepared before the first fly wave is critical.
The flies
Female blowflies (Lucilia cuprina) lay up to 3,000 eggs over 3 weeks. In ideal conditions, L1 larvae hatch out in 12 hours. These first stage larvae cause no problems, but in 3 to 10 days they moult to second and third stage larvae, and it’s these that cause fly strike. The L3 larvae pupate in the soil and in 3 to 7 days develop into the adult fly.
Products preventing flystrike
Insect growth regulators (IGRs) interfere in this life cycle and are one of a number of chemical groups used to prevent blowfly strike. Crookwell Veterinary Hospital stocks two IGRs – Cyrofly 60 and Clik.
Cyrofly 60 is a spray-on that provides up to 11 weeks protection from blowfly strike on long wool sheep (including organophosphate resistant fly strains). Its active chemical cyromazine prevents fly strike by stopping the moulting of the benign L1 into the harmful L2 stage.
Cyrofly 60 is contraindicated for use on open wounds, including mulesing and marking, and its effectiveness is reduced in sheep with less than 6 weeks of wool.
Clik provides 16 to 24 weeks protection. A ready-to-use spray-on formulation, Clik (dicyclanil) works in a similar way by preventing the moulting of treated larvae into the next larval stage. Clik is effective on all wool lengths, including off-shears, and is safe to use on mulesing and marking wounds.
Both products are preventative – that is, they should be used before an anticipated fly wave as the first stage larvae are the most susceptible and established strikes may not respond well to treatment.